Strumigenys feae Emery, 1895 - First recorded in Hong Kong as S. formosensis in Bolton (2000); see comments below

Tang, Kit Lam, Pierce, Mac P. & Guenard, Benoit, 2019, Review of the genus Strumigenys (Hymenoptera, Formicidae, Myrmicinae) in Hong Kong with the description of three new species and the addition of five native and four introduced species records, ZooKeys 831, pp. 1-48 : 10-11

Strumigenys feae Emery, 1895 - First recorded in Hong Kong as S. formosensis in Bolton (2000); see comments below Fig. 3 A–B

Strumigenys feae Emery 1895: 473 (w.q.) MYANMAR. Indomalaya.

Material examined.

HONG KONG: Tai Po District, Tai Om, 22.43681N, 114.1373E, 07.08.2015, 138 m, T. Tsang, Winkler, IBBL; Tsuen Wan District, Shing Mun, 22.40027N, 114.161E, 04.09.2015, 366 m, T. Tsang, Winkler, IBBL; Tuen Mun District, Castle Peak, 22.389935N, 113.954937E, 30.06.2015, R.H. Lee, pitfall trap, IBBL; Yuen Long District, Kap Lung, 22.41596N, 114.1038E, 11.09.2015, 288 m, T. Tsang, Winkler, IBBL; Sha Tin District, Tai Po Kau Nature Reserve, 22.4285N, 114.1808E, 22.02.2017, B. Guénard, Winkler, IBBL; Tai Po District, Kadoorie Farm and Botanic Garden, 22.43076N, 114.1215E, 04.07.2011, 335 m, P. Ward, sifted litter, IBBL.

Measurements.

Workers (n = 2): TL 3.1-3.3, HL 0.81-0.87, HW 0.52-0.55, MandL 0.39-0.41, SL 0.52-0.53, EL 0.061-0.062, PW 0.26-0.28, ML 0.82, PL 0.30, PH 0.15-0.16, DPW 0.11-0.12, PPL 0.19-0.20, GL 0.58-0.71, CI 63-64, MI 47-48, SI 96-100, OI 11-12, LPI 51-52, DPI 37-40.

Ecology.

In Hong Kong, S. feae was collected within tree plantations of Lophostemon confertus Wilson & Waterh. and in secondary forests, with elevation ranging from 138 to 457 m.

Comments.

While S. formosensis (Forel, 1912) has been recorded from Hong Kong ( Bolton 2000), we consider these records as S. feae . Strumigenys formosensis was initially described as a subspecies of S. feae , and Brown (1949: 24) raised S. formosensis to the species level without strong justification and without examining specimens of S. feae , writing: "Although I have seen no specimens of Emery’s Burmese species feae , I am arbitrarily raising the Taiwan form to species rank.", on the basis of Forel’s description of S. formosensis having small propodeal teeth and a strongly concave posterior mesosomal dorsum, with this latter information absent in Emery’s description of S. feae . The examination of the pictures of the type specimen of S. feae available on AntWeb (CASENT0904951), however, show the presence of a concavity between the mesonotum and propodeum, and with propodeal spines of the type of S. formosensis (CASENT0909309) indistinctly smaller than S. feae .

The revised descriptions of S. feae and S. formosensis by Bolton (2000) also revealed no clear distinction between them except the difference in morphological measurements, the length and morphology of the preapical teeth ("not directed medially but instead so strongly inclined toward the apicodorsal tooth that its proximal margin forms a single continuous line with the inner mandibular margin" for S. formosensis ), and brief mentioning of the maximum diameter of the eye compared to the width of the scape ("slightly greater" for S. feae and "equal to or slightly less" for S. formosensis ), with the rest of the descriptions almost identical to one another.

Specimens collected in Hong Kong could not be assigned to either S. feae or S. formosensis without ambiguity under the current descriptions. Preapical teeth are neither fully directed medially as in S. feae , nor with a single continuous proximal margin as in S. formosensis (Fig. 3). Morphological measurements also give little additional information. Measurements of the specimen ANTWEB1017082 (Fig. 3A), which has more forward-inclined preapical teeth, fall within the norm of S. formosensis as expected, specimen RHL01266 (Fig. 3B) with more medially-directed preapical teeth has some of its measurements closer to S. formosensis than to S. feae (Table 1). Considering the fact that S. formosensis was raised to its current species level somewhat arbitrarily, the validity of S. formosensis as a species would require further investigation using specimens from a wider geographic range than is available for this study.